Table of Contents
- Introduction
- The History of Cannas as a Food Crop
- Rhizomes vs. Bulbs: Understanding the Plant
- Ornamental vs. Edible Canna Varieties
- What Do Canna Rhizomes Taste Like?
- How to Harvest Canna Rhizomes for Eating
- Preparing and Cooking Canna Rhizomes
- Beyond the Rhizome: Other Edible Parts
- Safety and Precautions
- Growing Cannas for Both Beauty and Harvest
- Realistic Expectations for Gardeners
- Conclusion
- FAQ
Introduction
Cannas are the undisputed heavyweights of the summer garden. With their towering stems, oversized tropical leaves, and vibrant blooms, Cannas bring an exotic energy to any backyard. Most of us at Longfield Gardens value these plants for their incredible visual impact, especially varieties like the dark-foliaged ‘Black Knight.’ However, beyond their beauty, many gardeners find themselves asking a fascinating question: can you eat canna bulbs?
The answer is a resounding yes, though there is more to the story than simply digging them up and taking a bite. In this guide, we will explore the history of cannas as a food source, the difference between ornamental and agricultural varieties, and how to safely prepare canna bulbs. Whether you are interested in historical food crops or just curious about the plants in your landscape, you will discover that cannas offer much more than just a pretty face.
The History of Cannas as a Food Crop
While we usually think of cannas as decorative plants, they have a long and storied history as a staple food. The specific species most often grown for food is Canna edulis, also known as Achira. Native to the Andes Mountains in South America, this plant has been cultivated for thousands of years. Archeological evidence suggests that ancient civilizations in Peru were growing cannas for their starchy roots long before they became popular in European or North American gardens.
In many parts of the world, canna rhizomes (the correct botanical term for what we often call "bulbs") are still a vital source of nutrition. In Vietnam and Southern China, the starch extracted from these roots is used to make high-quality cellophane noodles. In the Andes, the roots are traditionally roasted or boiled, much like a potato or a sweet potato. The versatility of the plant allowed it to spread from South America to the Caribbean, Asia, and the Pacific Islands, proving its worth as a reliable and hardy food source.
Rhizomes vs. Bulbs: Understanding the Plant
In the gardening world, we often use "bulb" as a catch-all term for any plant that grows from an underground storage organ. However, to understand how to eat or grow them, it helps to be a little more specific. Cannas grow from rhizomes.
A rhizome is a thick, fleshy stem that grows horizontally just beneath the soil surface. Unlike a true bulb (like a tulip), which is made of layers of leaves, a rhizome is a solid piece of plant tissue that stores energy in the form of starch. This high starch content is exactly why they were targeted as a food source by ancient farmers. When you look at a canna rhizome, you will see "eyes" or growing points, similar to those on a potato. Each of these eyes has the potential to sprout a new stalk, making the plant incredibly productive.
Ornamental vs. Edible Canna Varieties
It is important to distinguish between the cannas bred for beauty and those bred for the table. While almost all canna rhizomes are technically non-toxic and edible, they are not all created equal when it comes to flavor and texture.
Agricultural Cannas (Achira)
Canna edulis is the primary species grown for consumption. These plants are selected for their large, smooth rhizomes that are low in fiber and high in starch. They tend to have smaller, less showy flowers compared to the varieties found in a typical flower garden, as the plant’s energy is directed toward the underground roots rather than the blooms.
Ornamental Cannas
The cannas we typically sell and grow in our flower beds, such as the striking 'Black Knight,' are bred for their magnificent foliage and large, colorful flowers. While you can technically eat the rhizomes of these ornamental types, they are often much more fibrous and woody than their agricultural cousins. They may also be smaller, making the effort of harvesting and cleaning them less rewarding. However, if you are simply curious about the taste, an ornamental canna rhizome will provide a similar, albeit tougher, experience to the traditional food variety.
What Do Canna Rhizomes Taste Like?
If you decide to try a canna rhizome, do not expect a burst of intense flavor. They are quite mild, often described as having a taste somewhere between a potato, a water chestnut, and a jicama.
The primary appeal is the texture and the starch content. When raw, the rhizomes are crisp and slightly sweet. When cooked, they become soft and starchy, though they can remain somewhat fibrous depending on the age of the plant. The starch itself is unique because it has very large granules. In the world of nutrition, this makes canna starch exceptionally easy to digest. This is why canna flour or arrowroot is often recommended for people with sensitive digestive systems or for use in baby foods.
How to Harvest Canna Rhizomes for Eating
If you want to sample your garden's bounty, timing and technique are key. The best time to harvest for eating is the same time you would lift your cannas for winter storage—usually right after the first frost has blackened the foliage.
- Cut the Stalks: Trim the foliage down to about four inches above the ground.
- Dig Carefully: Use a garden fork to gently lift the entire clump from the soil. Work in a wide circle around the plant to avoid slicing through the fleshy rhizomes.
- Select the Best Pieces: For eating, look for the youngest, freshest parts of the rhizome. These are usually the outer edges of the clump. The older, central parts of the root system tend to be much more woody and tough.
- Clean Thoroughly: Canna rhizomes have many nooks and crannies where soil can hide. Use a stiff brush and plenty of water to scrub them completely clean.
- Peel: The outer skin can be thick and dirty. Use a vegetable peeler or a sharp knife to remove the skin until you reach the white or cream-colored flesh inside.
Key Takeaway: Always choose the youngest, outermost growth of the rhizome for the best texture and flavor. Older sections are best left for replanting next year.
Preparing and Cooking Canna Rhizomes
Once cleaned and peeled, canna rhizomes can be prepared in several ways. Because they are so starchy, they behave very much like other root vegetables.
Boiling and Mashing
This is the simplest method. Cut the peeled rhizomes into uniform chunks and boil them in salted water until they are tender. This can take longer than a potato—often 20 to 30 minutes. Once soft, they can be mashed with butter or milk. Be aware that even well-cooked cannas can have some "strings" or fibers, so you may want to pass the mash through a sieve for a smoother texture.
Roasting
Roasting brings out the slight sweetness of the rhizome. Toss chunks with olive oil, salt, and herbs, then roast at 400°F until the outside is golden and the inside is soft. This method works best with very young rhizomes that are less likely to be woody.
Making Canna Starch (Arrowroot)
For those who want to get adventurous, you can extract the starch to use as a thickener for soups and sauces. This involves grating the cleaned rhizomes into a pulp, mixing the pulp with water, and then straining it through a fine cloth. The "milk" that strains out is full of starch. If you let this liquid sit, the starch will settle to the bottom. You can then pour off the water, dry the white sediment, and grind it into a fine powder. This is the traditional way to make "Achira" flour.
Beyond the Rhizome: Other Edible Parts
The rhizome isn't the only part of the canna plant that has found its way into the kitchen. In various cultures, other parts of the plant are utilized for both flavor and function.
- Young Shoots: In some Asian cuisines, the very young, emerging shoots of the canna plant are harvested and eaten as a green vegetable. They are typically blanched or stir-fried and have a mild, slightly vegetal taste.
- Leaves: While the leaves themselves are too fibrous to eat, they are frequently used as food wraps. Similar to banana leaves, canna leaves are excellent for wrapping tamales, fish, or rice before steaming or grilling. They impart a very subtle herbal scent to the food and help keep it moist during the cooking process.
- Seeds: Canna seeds are incredibly hard—so hard they were once used as "Indian Shot" for muskets. Because of this, they are rarely eaten. However, in some regions, they are ground into a meal, though this requires significant effort and is not common in modern cooking.
Safety and Precautions
Before you head out to the garden with a shovel and a fork, there are a few very important safety considerations. While the plant itself is non-toxic, the environment it grows in matters immensely.
Pesticides and Fertilizers
This is the most critical factor for home gardeners. Most ornamental plants are not grown with food safety in mind. If you have used systemic pesticides—chemicals that are absorbed by the plant's tissues to kill bugs—you should not eat any part of the plant. These chemicals can remain in the rhizomes for a long time. Similarly, if you use heavy chemical fertilizers that are not rated for edible crops, it is best to enjoy your cannas for their flowers only.
Soil Quality
Cannas are "heavy feeders," meaning they take up a lot of nutrients (and other substances) from the soil. Ensure your soil is clean and free of heavy metals or contaminants. If you are unsure of your soil's history, it is safer to grow cannas for food in large containers using fresh, organic potting mix.
Identification
Always be 100% certain that the plant you are digging up is a canna. While cannas are easy to identify by their large leaves and unique rhizomes, many other garden plants grow from bulbs or tubers that are highly toxic. If there is any doubt, do not eat it.
What to Do Next:
- Check your garden records to see what fertilizers or pesticides you have used this season.
- If you want to grow cannas specifically for eating, start a fresh "edible-only" container next spring.
- Use organic compost and food-safe fertilizers for any plants you intend to harvest.
Growing Cannas for Both Beauty and Harvest
At Longfield Gardens, we believe you shouldn't have to choose between a beautiful yard and a functional one. Cannas are the perfect example of a "dual-purpose" plant. You can enjoy the stunning red flowers of ‘Black Knight’ all summer long and then explore the culinary history of the canna bulbs in the fall.
To get the best results, whether for flowers or for food, remember that cannas are heat-loving plants. They need plenty of sun (at least 6 to 8 hours a day) and consistent moisture. Because they grow so fast and produce so much biomass, they appreciate a soil rich in organic matter. If you provide them with a little extra compost and regular water, they will reward you with massive growth both above and below the ground.
Realistic Expectations for Gardeners
It is helpful to remember that results will vary based on your climate and soil. In warmer zones (Zone 8 and above), cannas can stay in the ground year-round and will develop very large, multi-year rhizome clumps. In cooler northern climates, the growing season is shorter, so the rhizomes may be smaller and more tender. This actually makes them better for eating, though you will have a smaller harvest overall.
Always keep in mind that gardening is an experiment. One variety might produce a rhizome that is surprisingly delicious, while another might be too tough to enjoy. The joy is in the process of discovery.
Conclusion
Exploring the edible side of your flower garden is a wonderful way to deepen your connection with the plants you grow. Cannas are not just tropical showstoppers; they are ancient crops with a rich history of feeding people across the globe. While the varieties we grow today at Longfield Gardens are primarily selected for their breathtaking beauty, their roots remain a fascinating link to the past.
- Edibility: Almost all canna rhizomes are non-toxic, but agricultural species like Canna edulis are best for eating.
- Taste: Mild and starchy, similar to a potato or water chestnut.
- Preparation: Clean thoroughly, peel, and boil or roast like a root vegetable.
- Safety: Only eat plants that have been grown without systemic pesticides or non-food-safe chemicals.
Growing cannas is an accessible and rewarding way to bring a touch of the tropics to your home. Whether you are planting them for their bold foliage or their hidden culinary potential, these plants are sure to be a highlight of your gardening season.
FAQ
Are all canna lilies edible?
Technically, the rhizomes of most Canna species are non-toxic and edible. However, the ornamental varieties commonly found in flower gardens are often much more fibrous and less palatable than the specific agricultural species, Canna edulis. Always ensure your plants haven't been treated with systemic pesticides before sampling them.
Can I eat canna bulbs raw?
Yes, canna rhizomes can be eaten raw and have a crisp, slightly sweet flavor similar to jicama. However, they are quite starchy and are generally more enjoyable when cooked, which softens the fibers and makes the starch easier to digest. Make sure to peel them thoroughly before eating to remove the tough outer skin.
Are canna leaves toxic to pets?
Canna lilies are generally considered non-toxic to dogs, cats, and horses by the ASPCA. This makes them a great choice for pet-friendly landscapes. However, it is always a good idea to discourage pets from chewing on garden plants to avoid any potential digestive upset from the fiber content.
Is the "canna lily" the same as a "true lily"?
No, cannas are not true lilies. True lilies (Lilium) and daylilies (Hemerocallis) belong to different plant families and have different growth habits. While some parts of true lilies are edible in certain cultures, many are highly toxic, especially to cats. Always use the botanical name Canna to ensure you are identifying the correct plant.